Enigma: The Battle for the Code by Hugh Sebag-Montefiore

Author:Hugh Sebag-Montefiore [Sebag-Montefiore, Hugh]
Language: eng
Format: epub
ISBN: 9780470468845
Publisher: Turner Publishing Company
Published: 2017-05-20T16:00:00+00:00

20

Breaking the Deadlock

The Mediterranean and Bletchley Park

OCTOBER–DECEMBER 1942

As the German U-boats sank more and more ships off the east coast of America during the first half of 1942, another battle was being fought, between Britain and America, across the Atlantic. The Americans wanted to know why they were no longer receiving Naval Enigma intelligence from their new allies. The British did not want to tell them in case the information leaked out to the Germans. It was a reprise of an old row which had been bubbling away under the surface ever since the beginning of 1941.

The seeds of the row had been sown at the end of 1940 after-discussions had taken place about the possibility of an Anglo-American exchange of cryptographic secrets. On 15 November 1940 Alastair Denniston, the head of Bletchley Park, wrote to Stewart Menzies, the head of the Secret Intelligence Service: ‘As regards German and Italian [ciphers], any we may have is of such vital importance to us that we cannot agree at once to hand it over unreservedly. We should require to be informed in detail as to the security of such information after it left our hands.’1

Notwithstanding Denniston’s objections, the first American codebreaking liaison team arrived in Britain two and a half months later. They had instructions to reveal to their counterparts at Bletchley Park how the Americans had broken the Japanese code known as ‘Purple’. In return, they were hoping that they would be told all about British progress on German ciphers. However, while they were being greeted with glasses of sherry and tales of derring-do by Alastair Denniston at Bletchley Park and by Stewart Menzies, the head of the Secret Intelligence Service, these same men were conspiring behind the Americans’ backs to reveal as little as possible to them.

Even when Menzies mentioned to Churchill at the end of February 1941 that the chiefs of staff were willing to share the British cryptographers’ knowledge concerning the Enigma cipher with the Americans, there was a sting in the tail; Menzies stated that any discussions would not extend to ‘the results’, that is the intelligence gathered through reading Enigma messages. Churchill wrote the following note at the bottom of Menzies’ memo to signify his approval:– ‘As proposed. WSC.27.2’.2 The Americans were quickly sworn to secrecy, one of the naval representatives in the US liaison team signing a note agreeing to inform ‘by word of mouth only the head of our section, Commander L. F. Safford, USN’. The US Army representatives gave equivalent undertakings.3 The Americans were eventually given a ‘paper’ Enigma to take home with them.4

During the summer of 1941 Churchill went back on his agreement with Menzies; Churchill suggested that the Americans should be given Enigma intelligence to help the US deal with the growing threat to their ships posed by the U-boats. However Menzies refused to give way completely, writing back:–

I find myself unable to devise any safe means of wrapping up the information in a manner which would not imperil this source .

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